The counterpart of sadism is masochism, consisting of sexual fantasies, urges or behaviour that involves being beaten, humiliated[?], bound, tortured, or otherwise made to suffer, in order to enhance or achieve sexual excitement. The name is derived from that of 19th century author Leopold von Sacher-Masoch.

The term BDSM has been created to describe the quite common activities between consenting adults that contain sadistic and masochistic elements. Many behaviors such as erotic spanking and love-bites[?] that many people think of only as "rough" sex also contain elements of sado-masochism.

In certain extreme cases, sadism and masochism can include fantasies, sexual urges or behaviour that cause significant distress or impairment in social, occupational, or other important areas of functioning, to the point that they can be considered part of a mental disorder. However, this is an uncommon case, and psychiatrists are now moving towards regarding sadism and masochism as not being regarded as disorders in themselves, but only as disordered when associated with other problems such as a personality disorder.

Unfortunately, some disordered individuals commit crimes with a strong sadistic element. This is generally considered to be caused by personality disorders. Recently, there have been theories that many of these personality disorders have been caused by brain damage.